The present invention relates to an adhesive for bonding together a first substrate made of a vinylidene fluoride resin and a second substrate and thus for preparing a laminate which is in the form of, for example, film, sheet or composite cloth.
Vinylidene fluoride (VDF) resin, which is a general term referring to polyvinylidene fluoride (PVDF) or to VDF copolymer, is widely known as being resistant against corrosive chemicals and ultraviolet rays and as being superior in mechanical characteristics. Of fluororesins, VDF resin is particularly superior in extrudability and meltability for use as a powder coating or the like. Therefore, VDF resin is widely used as an anticorrosion coating for metal and as an electric wire coating. Furthermore, VDF has a superior characteristic as a barrier against gases, as compared with other fluororesins.
VDF resin film is widely used as a coating on a substrate, for providing the substrate with chemical resistance, stain resistance and the like. For example, there is provided a commercial VDF-resin product for an awning of truck and the like. In this product, a PVDF film having a thickness of about 5 .mu.m is stuck to a soft polyvinyl chloride sheet by an acrylic adhesive.
U.S. Pat. No. 4,472,557 discloses an elastic fluorohydrocarbon resin obtained by graft copolymerization of a fluorine-containing elastomeric polymer with a fluorine-containing crystalline polymer (e.g., PVDF). Japanese Patent Unexamined Publication JP-A-64-22547 discloses an elastic fluorohydrocarbon resin film stuck to a substrate by a polyurethane resin layer (adhesive). This elastic fluorohydrocarbon resin film is obtained by graft copolymerization of a fluorine-containing elastomeric polymer with PVDF.
However, conventional adhesives for bonding together VDF resin and another material are inferior to the VDF resin itself in weathering resistance, water resistance, heat resistance, and the like. Therefore, these adhesives may be deteriorated under a condition of outdoor use for a long period of time or under a condition of severe temperature and severe humidity. With this, for example, the VDF resin may peel off the adhesive.